Office of Technology Transfer – University of Michigan

Controlled PEGylation on Gold Nanoparticles for Higher Efficacy

Technology #5679

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Duxin Sun
Managed By
Tiefei Dong
Senior Licensing Specialist, Life Sciences 734-763-5332
Patent Protection
US Patent Pending
US Patent Pending


Gold nanoparticles (AuNPs) have been used as a multifunctional platform in biology and medicine. The various roles of AuNPs in these applications include contrast agents in optical imaging, sensitizers for diagnostic probes and vectors for photothermal therapy. To stabilize AuNPs, PEGylation of the colloidal gold is often applied. However, the applications of AuNPs are limited by the current synthesis approaches. One problem is that traditional PEGylation is achieved through addition of excess amount of thiol-terminated PEG molecules to replace the original capping ligands, making it impossible to control PEG-R density on AuNPs. Since the density of PEG-R is critical for both in vivo and in vitro application, the uncontrolled density limited the application of AuNPs. Another problem is that excessive amount of targeting ligands are added to conjugate to AuNPs, leading to different charge ratios of the AuNPs, and eventually nonspecific uptake of AuNPs.


The researchers reported a “living” PEGylation with the ability to control PEG-R density and targeting ligands on AuNPs, and to achieve optimal composition and charge ratios of PEGylation on AuNPs. Made by femtosecond laser ablation, the AuNPs have “naked” surfaces and do not need any capping ligands. This broadens the application of AuNPs. The new technology also allows the control of targeting ligand density on AuNPs and the sequential addition of PEG-R to AuNPs, making specific targeting ability and uniform charge possible. The technology could enhance targeting efficacy and reduce nonspecific uptake.


  • Therapeutics, Imaging agents, medical device materials


  • Improved cancer cell targeting efficacy
  • Reduced nonspecific uptake